The present invention relates to a flip-up type hood whose rear end is tipped up when a traveling vehicle collides with an object, in view of enhancing absorbing efficiency of an impact of the object collapsing onto the hood.
The flip-up type hood of this kind is applicable to a hood for covering the upside of an engine room on the front side of a vehicle. This hood has its rear end connected to a vehicle body through a hood hinge and the front end engaged with the vehicle body through a hood lock. Normally, unlocking of the hood lock allows the hood to be opened. Then, the front end of the hood is moved upwardly about the hood hinge as a fulcrum.
When a vehicle comes into collision, at it front side, with an object, for example, a pedestrian, a flip-up force is applied on the rear end of the hood by an actuator. Consequently, the hood hinge's restriction to the rear end of the hood is cancelled, so that the hood is flipped up about the front end as a fulcrum. Such a mechanism is disclosed in Japanese Patent Application Laid-open (Hei) No. 10-119823 (page 5, FIG. 2).
Thus, this displacement of the rear end of the hood allows an interval between the hood and an engine to be increased, so that a displacement of the hood can be increased when the object interferes with the hood at a great acceleration, increasing absorption of impact energy. In this way, the disclosed mechanism is capable of suppressing damage on the object to the minimum.
In the earlier flip-up hood, it is necessary to complete the flip-up operation of the hood until an object on the collision interferes with the hood, requiring performance of the mechanism in a predetermined short time. In this view, the mechanism is configured so as to have an ability of exerting a great “flip-up” force on the hood in an instant.
Due to inertial mass of the hood itself, however, the mechanism's flip-up operation with a great “flip-up” force causes the hood to be flipped up excessively (so-called “overstroke” phenomenon). As a result, a fluttering motion of the hood is produced to reduce absorbing efficiency of impact energy on the object.